1. Field of the Invention
The present invention relates to computer systems, and particularly to hand held computers that are practical for data entry through either a keyboard input arrangement or a pen input arrangement.
2. Description of Related Art
A variety of hand held computers such as laptops and palm-top computers have become very popular and are widely used for both business and personal activities. Hand held computers typically include a keyboard portion hinged to a display portion. While user input to computing devices has been generally through a keyboard and mouse, pen computer capability (using recognition of handwritten inputs by a pen acting upon a display surface) is desirable for certain types of hand held computers, especially in mobile tasks that require a more limited extent of textual input. Mobile users often must enter data while standing, holding the computer in one hand (with the display open and firmly supported), and the pen in the other. In a sitting position, it should also be possible to use the pen with one hand while balancing the computer on the user's knee, leaving one hand free. In a particular setting, for example, hand held computers are used in business meetings for note taking purposes. Since the clicking of a keyboard may be disruptive in the meeting, a pen input arrangement allows the user to use the computer as electronic paper, thus avoiding disruptions in the meeting. Another advantage of pen computers is that non-textual information, such as drawings, graphs, or diagrams, may be recorded.
It has been recognized that a keyboard/pen arrangement would benefit many applications and users. Many hand held computers use a keyboard/pen arrangement for data entry, such as disclosed in U.S. Pat. No. 5,268,816 to Abell, and U.S. Pat. No. 5,276,589 to Bartlett. It is known in the art to use dual position display screens for keyboard/pen arrangements. When the display screen is in its substantially vertical position, the keyboard is disposed in a substantially horizontal position so that a user may view the display screen when using the keyboard to enter data. When data is to be entered through a graphics pen, the display screen is disposed in a substantially horizontal position, and the keyboard is disposed in a substantially vertical position. An example of such a system is disclosed in U.S. Pat. No. 5,103,376 to Blonder.
A problem with the known keyboard/pen computer arrangements is that the keyboard/mouse portion of the computer stays active and gets in the way when a user is entering data using a graphics pen. The user has to be careful not to hit a key accidentally, which would input erroneous data; therefore, the user cannot use the keyboard portion as a grip to keep the computer steady when using the graphics pen. This leads to computer designs that are larger in size and heavier in order to reduce the need for gripping. Since it is desired to keep the weight and size of a hand held computer to a minimum so that a user can carry the computer more easily, this increased weight and size is therefore not desirable. Another drawback of these devices is that the pen input is not automatically activated. Instead, a manual knob or a switch is needed to activate the keyboard/mouse input or the pen input.
Accordingly, a need exists to provide a simple and light-weight keyboard/pen computer interface such that the computer switches mode automatically to disable or activate the keyboard when appropriate. It would be further desirable to provide a keyboard/pen computer interface in which the keyboard does not interfere with the use of the computer when it is in a pen input mode.